1. Technical Field
The present disclosure relates to acoustic devices and, particularly, to a carbon nanotube based thermoacoustic device.
2. Description of Related Art
Acoustic devices generally include a signal device and a sound wave generator electrically connected to the signal device. The signal device inputs signals to the sound wave generator, such as loudspeakers. A loudspeaker is an electro-acoustic transducer that converts electrical signals into sound.
There are different types of loudspeakers, categorized according to their working principle, such as electro-dynamic loudspeakers, electromagnetic loudspeakers, electrostatic loudspeakers, and piezoelectric loudspeakers. These various types of loudspeakers use mechanical vibration to produce sound waves. In other words, they all achieve “electro-mechanical-acoustic” conversion. Among these various types, the electro-dynamic loudspeakers are the most widely used.
A thermophone based on the thermoacoustic effect was made by H. D. Arnold and I. B. Crandall (H. D. Arnold and I. B. Crandall, “The thermophone as a precision source of sound,” Phys. Rev. 10, pp 22-38 (1917)). A platinum strip with a thickness of 7×10−5 cm and a heat capacity per unit area of 2×10−4 J/cm2*K was used as a thermoacoustic element. However, the thermophone adopting the platinum strip produced weak sounds because the heat capacity per unit area of the platinum strip was too high.
What is needed, therefore, is to provide a thermoacoustic device having good sound effect and high efficiency.